50000 germs reach a person. The skin and the mucus stop 90% of them…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
germs reach a person. The skin and the mucus stop of them. The acid and the saliva stop of the germs that are left. Then the white cells destroy of the germs that are left after that.
- How many germs are left after the skin and the mucus?
- How many germs are left after the acid and the saliva?
- How many germs are left after the white cells?
Need a reminder? The key ideaShow
Innate immunity has four kinds of barriers: physical, physiological, cellular and cytokine. Each barrier acts on the germs that the barrier before it let through, so the shares multiply. The bone marrow and the thymus are the primary lymphoid organs. The spleen, the lymph nodes, the tonsils, Peyer's patches, the appendix and MALT are secondary lymphoid organs.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Start: germs. Shares stopped: , and .
Plan. At each barrier, keep the share that is not stopped.
Step 1. Skin and mucus. The share left is . germs.
Step 2. Acid and saliva. The share left is . germs.
Step 3. White cells. The share left is . germs.
Answer: ; ; germs.
Check. The total share that gets through is , and .
Watch out. The three shares are not added. The result of one barrier is the start of the next.
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